Conformational Isomorphism of Organic Crystals:  Racemic and Homochiral Atenolol

• Published in: Crystal growth & design Vol. 7; no. 3; pp. 496 - 500
• Main Authors: Esteves de Castro, R. A, Canotilho, João, Barbosa, Rui M, Silva, M. Ramos, Beja, A. Matos, Paixão, J. A, Redinha, J. Simões
• Format: Journal Article
• Language: English
• Published: Washington,DC American Chemical Society 01.03.2007
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystalline state (including molecular motions in solids); Exact sciences and technology; Growth from vapor; Materials science; Methods of crystal growth; physics of crystal growth; Organic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Theory of crystal structure, crystal symmetry; calculations and modeling; Crystal growth; Molecular flexibility; Space groups; Atomic position; Symmetry property; XRD; Evaporation; Atenolol; Crystal symmetry; Racemates; Alcoholic solution; X-ray diffraction analysis; Centrosymmetrical crystals; Organic compounds; Conformation; Crystal structure
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg0601857

X-ray diffraction analysis of (R,S)- and S-atenolol crystalline forms was performed. The crystals studied were grown from evaporation of an ethanol/water solution. (R,S)-Atenolol crystallizes in the centrosymmetric space group C2/c, and S-atenolol crystallizes in a noncentrosymmetric space group C2. There is one symmetry independent molecule in (R,S)-atenolol crystals and two symmetry independent molecules in S-atenolol. However, due to disorder, two different molecular conformations were identified in the (R,S)-atenolol, and three different conformations were isolated in S-atenolol. Flexibility of molecular segments of the carbon chain is seen in conformational isomorphism and in the atomic position uncertainty. The molecular conformations given by X-ray diffraction were fully relaxed at the HF/6-31G* level of theory. The optimized structure was used as reference in comparison with molecular conformation in the solid state.